Patent GB-1451447-A (GB)
Title: Friction welding
IPC: B23K20/12
Filed: 1972-09-07
Abstract: 1451447 Welding by pressure WELDING INSTITUTE 7 Dec 1973 [7 Sept 1972] 41594/72 Heading B3R In friction welding metal workpieces in a liquid environment a sleeve 4 is formed or placed, before the commencement of welding, closely round the abutting faces of the workpieces, the material of the sleeve being such that it is locally displaced by the welding upset and its thickness being such that its outer layer is not penetrated by the upset. The environment may be water or oil and the sleeve material may be expanded or foamed polystryene, or expanded polyurethane or stiff liquid plastics, grease or pellets of wood, metal or organic material in a sleeve shaped housing. If the workpieces are tubular a plug 5 may be inserted into the hollow ends, both sleeve and plug softening and the upset 3 flowing into them to result in an improved weld. For under water welding the sleeve preferably has an oily outer coating. The sleeve may be formed by injecting materials suitable for forming foamed plastics into a casing extending between the workpiece holders with the workpieces already in place or a block of expanded plastics material may be placed between the ends of the workpieces and at least one of the workpieces is rotated under axial pressure, the workpiece ends then cutting into the block to form a sleeve about them and if tubular a plug within them. Instead of rotating the major workpieces an insert workpiece can be rotated between them, the insert preferably being bonded within a sleeve of the material, which overlaps the ends of the insert, the sleeve being provided with an enlarged portion provided with flat driving surfaces. Alternatively two sleeves may be used one for each upset. A friction welding apparatus for carrying out the process underwater, to join a pipe to a flange, comprises a housing 11, Fig. 7, rotatably mounting a drive plate 12 in bearings 13 and, attached to the external surface of the housing, actuators 15 which support an annular housing 16. A hollow flange 14 is secured to the plate 12 and a tube 17 is fixed in the housing 16 by piston operated clamps 18, operation of the actuators 15 bringing the workpieces into abutment. The plate 12 is rotated by hydraulic, electrical or mechanical motors 21 which are powered and controlled by a source 24 which controls through an actuator 26 an expanding mandrel 27 located within the workpiece 17. About the ends of the workpieces is an annular container 30 connected to an injection device 22 which injects the sleeve forming material into the space 33 about the ends. A plug of the material is introduced by channels 36 in the plate 12 in communication with an annular distributor 35. The end faces of the workpieces need not be brought initially into abutment and the sleeve and plug forming material can be introduced into the container 30. The apparatus may alternatively have a built in magazine for blocks or sleeves with a device for dispensing them, one at a time, into welding position. A container may be mounted on a workpiece holder and may be open at least at its end facing the other holder to receive the sleeve. The method may be used for joining bars together or to flanges or to join bolts or sockets to structures when the sleeve abuts the structure. The welding may be inertia welding, oscillating welding or orbital welding.